eCompass
A compass to keep you on the right track.
Last updated
A compass to keep you on the right track.
Last updated
An eCompass is a tilt compensated electronic compass utilizing an accelerometer and a magnetometer. Those from ST Microelectronics provide very accurate acceleration and guidance. Having already worked with the LSM303AGR in the past, this is the solution I opted for.
ST's module offers a very low power system for very high performance. Its accelerometer coupled with a magnetometer, all in a 4mm^2 package, makes it a real eye-catcher.
The LSM303AGR is polyvalent: it can detect movement, provide orientation information, assist in dead-reckoning and much more. It's the perfect compass for the project.
To integrate this component, simply refer to the datasheet. Pin n°5 is connected to ground via a 220nF capacitor. The eCompass is supplied in 3.3V with three decoupling capacitors (see page 35 of the datasheet).
| Characteristic | Description |
|---|---|
| Pin Number | Symbol | Description |
|---|---|---|
Package
LGA-12 | 2x2x1mm
Acceleration Features
3 axes (X/Y/Z) ±2 / ±4 / ±8 / ±16g selectable full scales Avg of 3.7µA power consumption
Magnetic Features
3 magnetic field channels (X/Y/Z) ±50 gauss magnetic dynamic range Avg of 200µA power consumption
Resolution
16-bit data output
Speed Mode
100kHz, 400kHz, 1MHz, 3.4MHz
Operating Temperature
-40°C ti +85°C
Current consumption in power-down mode
~2µA
1
SCL
SPC
I2C serial clock SPI serial port clock
2
CS_ACC
Accelerometer: SPI enable
I2C/SPI mode selection
3
CS_MAG
Magnetometer: SPI enable
I2C/SPI mode selection
4
SDA
SDI
SDO
I2C serial data (SDA)
SPI serial data input (SDI)
3-wire interface serial data output (SDO)
5
C1
Capacitor connection (C1 = 220 nF)
6 & 8
GND
Connected to GND
7
INT_MAG
DRDY
Magnetometer interrupt
Data-ready signal
9
Vdd
Power supply
10
Vdd_IO
Power supply for I/O pins
11
INT_2_XL
Accelerometer interrupt 2
12
INT_1_XL
Accelerometer interrupt 1
